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Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338

News Release

April 11, 2005

U of G Prof Helps Uncover World’s Most Ferocious Biter

In a first-ever study, scientists from the University of Guelph and Australia dug into the fossil record to determine the mammal with the most powerful bite in the world. They also discovered that the bigger the brain, the wimpier the bite.

The findings of Guelph biomedical sciences professor Jeff Thomason and researchers from the University of Sydney and University of Newcastle appear in the prestigious British journal Proceedings of the Royal Society.

Delving into previously unexplored territory, the scientists compared the bite force of 39 species of mammalian predators, both living and extinct. Their sample ranged from cougars, hyenas and badgers to lions, tigers and bears.

A marsupial lion that roamed Australia during the Ice Age — Thylacoleo carnifex — emerged as the champion chomper. “Pound for pound, it was the hardest-biting animal ever,” Thomason said. It became extinct about 40,000 years ago.

Named for its cat-like appearance, the 200-pound marsupial lion had the most muscular jaws of any species and could bite with unrivalled force, the study found. It’s related to the koala and the wombat and had shearing teeth and sharp thumb-like claws.

This was the first time analyses of bite force were made in such a wide species sampling. The researchers used a scientific model developed by Thomason to do the comparisons. It allows predictions of bite force to be made based on skull dimensions, making it possible to compare animals that lived thousands of years ago with those still roaming the Earth today.

“If an animal exists only through the fossil record, you obviously can’t throw it a bone and see how it chews or observe it feeding in the wild,” Thomason said. “Before now, people could only look at a fossil and say, ‘Yes, it looks like it probably had a large bite.’”

Other strong-biting animals include the African hunting dog, Tasmanian devil and clouded leopard. Predators with weaker bites include black, brown and Asiatic bears, the leopard and the coyote. “Surprisingly, hyena bites also aren’t as forceful as we imagined,” Thomason said. “They can crunch through bone, but they don’t have the strongest bite for their body size.”

The study also found that carnivores with the largest brains had a smaller bite force. The thought is that brain volume impinges on available area for muscle development, reducing the power of the bite, Thomason said. On average, the brains of marsupials are about 2 ½ times smaller than those of other predatory species. “So the marsupial lion could certainly bite, but it probably wasn’t too bright.”

Biting aside, the study had another significant purpose. “We were interested in what bite force could tell us about how an animal may have fed and the size of the prey it could take down,” he said.

For example, large animals such as bears are known to feed on smaller-sized prey, and the research showed that their bite is weaker than that of other predators. By contrast, the African hunting dog can take down beasts 10 times its own body weight, and it was shown to have a forceful bite.

Based on the findings, Thomason speculates that the marsupial lion regularly preyed on animals twice its size. “It tells us they weren’t feeding on opossums.”

He added that the study is important in paleontology because it shows that not only can bite force be calculated but also that estimates of bite force can be used to indicate what animals were eating and what their feeding patterns may have been. “Once you do that, you can start building the structure of communities in fossil samples,” Thomason said.

Prof. Jeff Thomason
Department of Biomedical Sciences
(519) 824-4120, Ext. 54934

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